In the older German Patent Application No. DE 199 49 507 A1 by the present applicant several gearbox designs for an automatic multi-stage gearbox with various combinations of coupled planetary gear sets are described. By a suitable connection of a non-shifting reduction planetary gear set combination to a shiftable main planetary gear set combination, at least seven respective forward gears can be engaged without range-change. The number of engageable forward gears is here at least two more than the number of shift elements. The reduction and main planetary gear sets are in this case always arranged coaxially with one another.
For the above case DE 199 49 507 A1 proposes that the shiftable main planetary gear set combination be made as a two-web/four-shaft transmission with two shiftable main planetary gear sets. Here, two-web/four-shaft transmission is understood to mean an arrangement of two individual mechanically coupled one-web planetary gear sets, in which the coupled unit has four so-termed “free shafts” owing to duplicated component connection, where a “shaft” can be a solar gearwheel, an annular gearwheel or even a web of a planetary gearwheel assembly.
Starting from the said state of the art, the purpose of the present invention is to provide a multi-stage gearbox with a non-coaxial arrangement of the drive input and drive output shafts and at least seven forward gears that can be engaged without range-change, developed further in relation to structural volume, with comparatively low construction cost, suitable gear ratio steps and a larger spread.